Metabolomics of stomatal immunity in the disease triangle

Crops are continually exposed to microbial pathogens, which cause plant disease, leading to severe yield loss. A major route of pathogen entry into plants is through microscopic pores formed by pairs of guard cells on leaf surfaces. The pores are called stomata, through which plants release oxygen and water vapor and take up carbon dioxide (CO2) from the atmosphere. The CO2 is used for synthesizing carbohydrates and other biomaterials/metabolites. The goal of this research is to understand how metabolites in guard cells play regulatory roles in pathogen-triggered stomatal movements in the context of other environmental conditions, such as drought and rising CO2 in the atmosphere. The investigations will improve understanding of the mechanisms that link stomatal aperture to environmental conditions and diseases. Because guard cells dynamically control the size of the stomatal pore and thus control pathogen entry, CO2 uptake and plant water loss, their function impacts plant growth and yield. A better understanding of plant stomatal movements should foster rational crop breeding and engineering for enhanced disease resistance and yield. Since metabolite regulation is ubiquitous in biology the research will have broad impact. The project will enable cross-disciplinary training of students (including women and underrepresented groups). Since plant metabolites are tightly related to our daily lives, the “Plant Metabolites” outreach activities will extend to the general public. Exposing students and the public to modern scientific research will contribute to preparing highly qualified future scientists and citizens, who will contribute to building a prosperous society and a sustainable world. The research team will apply molecular genetics and omics approaches to assess the functions of metabolites in regulating guard cell and mesophyll processes and stomatal movements during pathogen response. The central hypothesis is that changes in guard cell metabolites play important regulatory roles in pathogen-triggered stomatal movements in the context of different environmental conditions, particularly drought and rising CO2. The hypotheses will be evaluated with three objectives: A) Quantify metabolite changes during pathogen-triggered stomatal closing and re-opening using LC-MS and GC-MS approaches. B) Verify roles of pathogen-related guard cell metabolites in stomatal aperture regulation and characterize interactions in different environmental conditions using reverse genetics and pharmacology. C) Elucidate guard cell networks of pathogen-induced stomatal closure and re-opening. The experiments will identify metabolites essential for stomatal movement in the context of bacterial disease and different environmental factors. The project will reveal novel regulatory mechanisms underlying pathogen-induced stomatal movements and will contribute to the emerging concept of metabolite regulation as a versatile mechanism by which cells regulate important signaling and metabolic processes. The knowledge that will be generated can inform rational crop breeding/engineering to improve stomatal defense without disruption of other pathways that impact crop yield. This award is co-funded by the Plant Biotic Interactions program and the Cellular Dynamics and Function cluster in the divisions of Integrative Organismal Systems and Molecular and Cellular Biosciences, respectively. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.